In telecommunications networks, presence information (or presence state) conveys the ability and willingness of a potential communication partner (e.g., a user, etc.) to communicate. Presence information for a user is typically provided to a presence service by a user client that resides and executes on a telecommunications terminal (e.g., a cell phone, a notebook computer, a “netbook” computer, a smartphone, etc.). The presence service typically stores this information in a personal availability record called a presentity that can be made available for distribution to other users (called watchers).
Presence information has wide application in many communication and computing services and is one of the innovations driving the popularity of instant messaging (IM) and Voice over Internet Protocol (VoIP) telephony. Some telecommunications systems employ presence information across a plurality of telecommunications channels and terminals, creating an aggregated view of user presence known as Multiple Points of Presence (MPOP).
In some situations presence information might be automatically inferred from passive observation of a user's actions. For example, a user who is engaged in an instant messaging (IM) session and is inactive for a given time interval might be inferred to be “away” or “unavailable”. Similarly, presence information might be inferred in other ways, such as, for example, based on: whether a user's telecommunications terminal is powered on or off; whether a user is logged into his or her computer; the contents of a calendar (or schedule) for one or more users; and so forth.